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• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
  • C08G77/26—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen nitrogen-containing groups
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  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
  • C08L83/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
  • C08G77/08—Preparatory processes characterised by the catalysts used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
  • C08G77/18—Polysiloxanes containing silicon bound to oxygen-containing groups to alkoxy or aryloxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/388—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/541—Silicon-containing compounds containing oxygen
  • C08K5/5415—Silicon-containing compounds containing oxygen containing at least one Si—O bond
  • C08K5/5419—Silicon-containing compounds containing oxygen containing at least one Si—O bond containing at least one Si—C bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/541—Silicon-containing compounds containing oxygen
  • C08K5/5425—Silicon-containing compounds containing oxygen containing at least one C=C bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/544—Silicon-containing compounds containing nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2312/00—Crosslinking
  • C08L2312/08—Crosslinking by silane

Definitions

• the present invention relates to a preparation for producing a polymer crosslinkable by a condensation reaction, a polymer mass crosslinkable by a condensation reaction, a method for producing a silicone elastomer and a silicone elastomer produced by the method.
• Silicone elastomers are characterized by their very good soft, elastic properties. Attempts have been made to produce silicone elastomers by cold crosslinking of hydroxy-terminated polydimethylsiloxanes with ethoxysilanes, the vulcanization taking place through the action of atmospheric moisture. However, it turned out that even if the air humidity is excluded, stiffening or even hardening cannot be prevented. The production of a polymer mass which can be stored in the absence of atmospheric moisture has thus hitherto not been possible.
• the present invention relates to a preparation for producing a polymer which can be crosslinked by a condensation reaction.
• the preparation contains at least one aminopropyltriethoxysilane and at least one polydialkylsiloxane with two terminal hydroxyl groups.
• the polydialkylsiloxane has the following formula (1): HO - [- SiR 1 R 2 -O-] x -OH Formula (1) where in formula (1) R 1 and R 2 can be the same or different and are selected from alkyl groups having 1 to 8 carbon atoms and where x is an integer from 30 to 2500.
• the polydialkylsiloxane preferably has a viscosity at 23 ° C., measured according to ISO 3219 of 1993, of 20,000 to 350,000 mPa ⁇ s, which improves the incorporation of the aminopropyltriethoxysilane so that a homogeneous mass can be worked out.
• the polydialkylsiloxane polydimethylsiloxane is also advantageous.
• the preparation can be obtained by simply mixing the components mentioned above and can be stored for a long period of time in the absence of moisture without changing, decomposing or reacting.
• the preparation can thus be produced in a simple manner and used to produce a polymer which can be crosslinked by a condensation reaction.
• the preparation can contain further components, provided that they do not trigger or maintain a premature reaction of the components essential to the invention contained therein.
• the aminopropyltriethoxysilane is preferably selected from 3-aminopropyltriethoxysilane, cyclohexylaminopropyltriethoxysilane and N- (2-aminoethyl) -3-aminopropyltriethoxysilane.
• a mass ratio of the polydialkylsiloxane to the aminopropyltriethoxysilane is preferably 20: 1 to 50: 1.
• a mass ratio of about 31: 1 to 36: 1 is particularly advantageous.
• the preparation preferably contains at least one silicone plasticizer, the silicone plasticizer being selected in particular from trimethylsiloxy-terminated polydimethylsiloxanes with a viscosity at 23 ° C., measured according to ISO 3219 of 1993, of 35 to 1000 mPas.
• a polymer composition crosslinkable by a condensation reaction contains the storage-stable preparation according to the invention described above.
• the polymer composition contains at least one ethoxy-functional crosslinking agent for crosslinking the polydialkylsiloxane contained in the preparation, the crosslinking agent in particular being at least one ethoxy-functional silicon-containing crosslinking agent in order to further improve the silicone properties.
• the polymer composition contains at least one further aminopropyltriethoxysilane, which can be the same or different from the aminopropyltriethoxysilane contained in the preparation.
• the polymer mass is still stable in the absence of moisture, but can react to a silicone elastomer when exposed to moisture (humidity or the addition of water), at least the aminopropyltriethoxysilane reacting with the polydialkylsiloxane from the preparation and the ethoxy-functional crosslinking agent to form a silicone elastomer by condensation reaction.
• the silicone elastomer produced from the polymer mass is characterized by soft, elastic properties as well as good mechanical and physical properties.
• the polymer mass can contain further functional components, such as colorants, polymerization inhibitors, fillers, pigments or fragrances.
• the ethoxy-functional crosslinking agent is preferably selected from methyltriethoxysilane, vinyltriethoxysilane, tetraethylsilicate, a partial hydrolyzate of tetraethylsilicate and 1,2-bis (triethoxysilyl) ethane.
• the polymer mass can preferably also contain at least one filler.
• at least one crosslinking catalyst can alternatively or additionally be provided to accelerate the polymerization reaction.
• Suitable fillers include, in particular, quartz or quartz powder, chalk, diatomaceous earth, calcium silicate, titanium oxide, iron oxide, zinc oxide, calcium carbonate, pyrogenic, highly disperse silica, precipitated silica and carbon black.
• Suitable crosslinking catalysts include titanium compounds, zirconium compounds, zinc compounds, aluminum compounds or tin compounds.
• Highly disperse silica has proven to be a particularly suitable filler, as it increases the mechanical strength of the silicone elastomer, such as the tear strength according to ASTM D624-00 (2012).
• Zinc bis (2-ethylhexanoate) has proven particularly useful as a crosslinking catalyst, since it has a high reactivity, is easy to buy and is obviously toxicologically harmless in contrast to tin catalysts in use.
• a method for producing a silicone elastomer is described as a further aspect of the invention.
• the method here initially comprises a step of producing a preparation for producing a polymer which can be crosslinked by a condensation reaction.
• the preparation can be designed like the preparation disclosed above and can be produced by mixing.
• the preparation thus contains at least one aminopropyltriethoxysilane and at least one polydialkylsiloxane with two terminal hydroxyl groups, which has the following formula (1): HO - [- SiR 1 R 2 -O-] x -OH Formula (1) where in formula (1) R 1 and R 2 can be the same or different and are selected from alkyl groups having 1 to 8 carbon atoms and where x is an integer from 30 to 2500.
• the preparation obtained in this way is storage-stable with exclusion of moisture and in a next process step must be stored with exclusion of moisture at room temperature for a period of at least 9 days to 12 weeks before it can be further processed.
• a storage time of about two weeks is advantageous, while storage times of less than 9 days are not sufficient.
• the reason for the storage is probably that the reaction of the aminopropyltriethoxysilane with the hydroxyl end groups of the polydialkylsiloxane proceeds very slowly and it is therefore advantageous to wait for an extensive degree of conversion.
• Premature use of the preparation for the production of the polymer mass causes stiffening or even hardening, so that filling into a moisture-tight container is not possible. It is presumably necessary to largely remove the hydroxyl end groups in order to achieve a desired level
• At least one ethoxy-functional crosslinking agent is added to the stored preparation, which is in particular at least one ethoxy-functional silicon-containing crosslinking agent selected in particular from methyltriethoxysilane, vinyltriethoxysilane, tetraethylsilicate, a partial hydrolyzate of tetraethylsilicate and 1,2-bis- (ethoxysilyl) .
• at least one further aminopropyltriethoxysilane is added to the stored preparation, it being possible for the aminopropyltriethoxysilane to be the same or different from the aminopropyltriethoxysilane contained in the preparation. This mixture gives a reaction mixture for the subsequent polymerization reaction, which is carried out as a condensation reaction.
• the reaction mixture reacts under the influence of moisture by means of condensation of the amine-functionalized polydialkylsiloxane, the aminopropyltriethoxysilane and the ethoxy-functional crosslinking agent.
• the moisture can in particular be introduced through air humidity, which promotes a particularly uniform polymerization reaction. Alternatively, a defined amount of water can also be added.
• a silicone elastomer with very good soft-elastic, physical and mechanical properties can be produced in a simple and cost-effective way by the method.
• the method according to the invention can be implemented without high technical effort.
• the method can further comprise a step of adding at least one crosslinking catalyst to the stored preparation.
• a silicone elastomer that can be produced by the method according to the invention is also described as a further aspect of the invention. It is characterized in that at least the polydialkylsiloxane, the aminopropyltriethoxysilane and the ethoxy-functional crosslinking agent are connected to one another by condensation, the ethoxy-functional crosslinking agent in particular composed of methyltriethoxysilane, Vinyl triethoxysilane, tetraethyl silicate, a partial hydrolyzate of tetraethyl silicate and 1,2-bis (triethoxysilyl) ethane is selected.
• the ethoxy-functional crosslinking agent in particular composed of methyltriethoxysilane, Vinyl triethoxysilane, tetraethyl silicate, a partial hydrolyzate of tetraethyl silicate and 1,2-bis (triethoxysilyl) ethane is selected.
• the silicone network is formed by reaction of the hydroxyl end groups of the polydialkylsiloxane with the ethoxy groups of the crosslinker, the hydroxyl end groups being formed by the action of moisture.
• the polymer then loses its free mobility. As a result, the flowability of the polymer mass is lost.
• a dialkylpolysiloxane with a viscosity of 80,000 mPa ⁇ s has an average of about 1,000 dimethylsiloxane units.
• the uncrosslinked as well as in the crosslinked state the polymer chains are not stretched, but rather disordered and twisted. The interaction of the polymer chains with one another is very slight.
• the network can be deformed even with a small amount of force; after the force is over, the original, disordered state is restored. The flowable or soft pasty polymer mass is thus converted into a soft elastic elastomer.
• Example 1 Production of a first preparation for the production of a polymer which can be crosslinked by a condensation reaction
• Example 4 Production of a fourth preparation for the production of a polymer which can be crosslinked by a condensation reaction
• composition A listed below were uniformly mixed in a paper drinking cup by means of a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• the skin formation time was approx. 60 minutes at 23.9 ° C. and 24% relative humidity.
• the skin formation time was determined in such a way that the surface of a freshly painted mass is lightly touched with the tip of a pencil at intervals of 3 minutes. The skin formation time is reached when there is no longer any mass left on the tip of the pencil.
• the Shore A hardness of the cured polymer mass was 23.
• Example 6 Production of a second polymer composition B which can be crosslinked by a condensation reaction
• composition B listed below were uniformly mixed in a paper drinking cup by means of a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• the skin formation time was approx. 45 minutes at 23.9 ° C. and 24% relative humidity.
• the skinning time was measured as described above.
• the Shore A hardness of the cured polymer mass was 26.
• Example 7 Production of a third polymer composition C which can be crosslinked by a condensation reaction
• composition C listed below were uniformly mixed in a paper drinking cup using a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• the skin formation time was approx. 60 minutes at 23.9 ° C. and 24% relative humidity.
• the skinning time was measured as described above.
• the Shore A hardness of the cured polymer mass was 24.
• Example 8 Production of a fourth polymer composition D which can be crosslinked by a condensation reaction
• Compound D listed below were uniformly mixed in a paper drinking cup using a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• Consistency 24 hours after production flows from the spatula.
• composition D For hardening, 40.0 g of composition D and 1.5 g of distilled water (3.75% by weight) were mixed in a paper drinking cup, filled into a small screw-top bottle lined with a release film and stored closed. After 18 hours, the contents of the screw-top bottle were vulcanized to dryness.
• the processing time was determined with another sample of the mass. For this purpose, a spatula was dipped into the mass and pulled out again. As long as the compound flowed off the spatula, the end of the processing time was not yet reached. The end of the processing time was reached when the strand of the flowing mass broke off and pulled back a little upwards and thus shortened.
• the processing time of Composition D by this method was 35 minutes at 25 ° C. and 23% relative humidity.
• composition E listed below were uniformly mixed in a paper drinking cup by means of a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• Consistency 24 hours after production flows from the spatula.
• composition E Processing time of composition E at 24.4 ° C. and 24% relative atmospheric humidity: 75 minutes, the processing time being determined as indicated in Example 8.
• the components of the mass F listed below were uniformly mixed in a paper drinking cup by means of a narrow spatula and filled into a screw-top jar and then stored closed with exclusion of moisture.
• Consistency 24 hours after production flows from the spatula.
• composition F The processing time of Composition F at 24.4 ° C. and 24% relative humidity, measured as in the preceding examples, was 15 minutes.
• Example 5 Glass + + + Acrylic glass (plexiglass) + - + Copper pipe + + + Spruce wood, lath + + + Polystyrene, plate + + + Tile, glazed + + + Tinplate + + + steel plate + + + PVC, pipe + + + ABS, plate + + + Aluminum, foil + + + +
• Example 10 Glass only edge adhesion + + Acrylic glass (plexiglass) + + - Tinplate + + + Aluminum foil + + + steel plate + + + Copper pipe + + + Tile, glazed - + - Concrete slab + + + Spruce wood, lath + + + ABS, plate + + + PVC, pipe + + - Polystyrene plate + + -
• Example 13 Influence of the water dosage on the vulcanization behavior
• the 4 mixtures were each poured into small screw-top cans lined with separating film, resulting in a layer thickness of approx. 1 cm. After a storage time of 24 hours at 24 ° C. and 23% relative humidity, the vulcanization status of the samples was checked.
• Example 14 Production of flowable compositions with highly disperse silica (Wacker, HDK® V 15)
• Achieving flowability depends on the process: If the hydrophilic, highly disperse silica was mixed in at the end of the batch, the result was a firm, pasty consistency, as is desired for one-component compounds.
• hydrophilic, highly dispersed silicic acid was mixed into the initially charged polymer to form a "stiff phase" and only subsequently the low-viscosity formulation components (crosslinker, catalyst, possibly adhesion promoter), then a flowable end product was formed, as is usually desired for two-component compounds.

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